Best way to cut MDF or plywood for corner shelving?

[Missnearlyvintage]

So, as in the title, we're trying to design some corner shelves in our lounge to fit in on the side of the chimney breast, and make use of dead space which lurks behind a permanently opened door.

I have the measurements needed, and have rung around the most decently rated timber merchants in the area, but they've not been keen on cutting the material for us on account of the shelves effectively being right angle triangle shaped.

We only have a mitre saw at present which will not be suitable, so I'm not sure whether to invest in a jigsaw and try and get the straightest edge that we can (it'll be the front edge we'd need to cut so we'd always see it if it's wonky!), or pay for a joiner to cut the wood for us?

I'd like to do it nicely, but it was supposed to be a relatively cheap project as I didn't know that timber merchants don't like triangles when I saw them advertising sheet material cutting services! We only need 4 shelves cutting!

Thanks everyone

A jigsaw won't give you a straight cut. If you're going down the power-tool route, you'd want a circular saw.

Have you tried cutting it youself with a hand saw? With a decent sharp saw it should be reasonably easy to get a good straight cut. With a bit of sanding and painting, you should be able to do a job that nobody could tell was DIY..

Some branches of B&Q will cut timber bought from their stores to order.